Modification Of Poly (Butylene Succinate)(PBS)/Ethylene-Vinyl Acetate Copolymer (EVA) And Preparation And Study Of Its Foams

Poly(butylene succinate)(PBS)is a kind of polyester that can be completely biodegraded,and it can be decomposed into carbon dioxide,water,methane,etc.when exposed to microorganisms or enzymes under appropriate conditions.PBS exhibits excellent mechanical properties,melt processability,biodegradability,thermal and chemical resistance compare to other aliphatic biodegradable polyesters.As a result,PBS and its products are widely used in our daily life.However,the low melt viscosity of PBS caused by low molecular weight and highly linear chain structure usually limits its further applications,especially in areas requiring sufficient melt viscosity,such as foaming molding.Herein,it is important to increase the viscosity of PBS in order to produce high performance PBS foams.The main methods to increase the melt viscosity of PBS are crosslinking via peroxide,chain extension and blending with other high viscosity polymers.Although many researchers have reported the preparation of PBS foams,few works focused on the mechanical properties of PBS foams.Therefore,the purpose of our work is to prepare PBS foams with proper mechanical properties and to broaden the applications.Firstly,high-melt-viscosity Ethylene Vinyl Acetate Copolymer(EVA)was introduced to improve the toughness and melt viscosity of PBS,then the best weight ratio of PBS and EVA was chosen when PBS/EVA composites owned best mechanical properties.Rheology test showed that the introduction of EVA and DCP could increase the complex viscosity of PBS notably.Moving Die Rheometer results indicated that the reaction rate of vulcanization and decomposition of blowing agent could be balanced well at160?.At last,PBS/EVA composite foams were prepared by traditional compression molding method.The effect of DCP,AC and crosslinking co-agent(TMPTMA)on the properties of PBS/EVA composite foams were studied in details.Results showed that the cell size was uniform and the density of foams could be as low as 0.25g/cm~3.Mechanical test revealed that PBS/EVA composite foams with 2phr DCP and AC had the highest specific flexural strength.Considering that EVA cannot be biodegraded,so the introduction of EVA may deteriorate the biodegradability of PBS/EVA composite foams.Hence,Wood Flour(WF)was introduced into PBS/EVA composites and then DCP was added to further increase the viscosity of PBS.Besides,silane coupling agent KH570 was used to modify WF to improve the compatibility of PBS/EVA and WF.The influence of WF content and KH570 on the properties of PBS/EVA/WF composites were investigated in details.Results revealed that the introduction of WF could remarkably increase the viscosity of PBS/EVA,this made it possible to prepare PBS/EVA/WF composite foams.Tensile test showed that the tensile strength of PBS/EVA/WF composites increased firstly and then decreased with the increase of WF content.KH570 could increase the rheology properties,tensile strength and compatibility of PBS/EVA/WF composites slightly.At last,based on the preparation of PBS/WF,EVA/WF foams and previous studies,PBS/EVA/WF composite foams were prepared successfully.The effect of WF on the properties of PBS/EVA/WF composite foams was studied.Results denoted that the prepared foams possessed closed and uniform cells.However,the uniformity of cells was deteriorated with the increase of WF content.Tensile test showed that the tensile strength of PBS/EVA/WF composite foams increased firstly and then decreased with the increase of WF content.When the WF content was 20 phr,PBS/EVA/WF composite foam had the highest tensile strength of 0.99 MPa.Degradation in alkali solution revealed that the microcellular structure and WF could increase the degradation of foams.Water absorption results showed that WF could increase while EVA could decrease the water absorption of PBS/EVA/WF composite foams.